160 Permanence and Evolution. 



chance they would have had against the spears 

 of the natives in an area of about ten miles 

 square. I by no means contend that this is the 

 sole cause, or perhaps even the chief cause, of 

 the paucity of mammals on small islands, but, 

 as I have said, I think it proved that there is 

 some cause hostile to their existence in such 

 places. 



By this and other considerations we are led 

 to the conclusion that the facts of distribution 

 can, to a great extent, be shown to have origi- 

 nated in an opposite manner, not by the 

 origination of new forms, but by the destruction 

 of old. 



On this subject we may see some suggestive 

 remarks in Dr. Andrew Murray's " Geographical 

 Distribution of Mammals," p. 2. On the one 

 hand an important argument for evolution is 

 supposed to be derived from the presence or 

 absence in small islands, etc., of certain large 

 classes of living forms, on the hypothesis that 



